Image fetching behavior

When fetching, rkt will try to avoid unnecessary network transfers.
For example, if an image is already in the local store, rkt will use HTTP's ETag and Cache-Control to avoid downloading it again unless the image was updated on the remote server.

This behavior can be changed by using the --pull-policy flag.
Usage of this flag is detailed in the image fetching behavior documentation.

Authentication

If you want to download an image from a private repository, then you will often need to pass credentials to be able to access it.
rkt currently supports authentication for fetching images via https:// or docker:// protocols.
To specify credentials you will have to write some configuration files.
You can find the format of the configuration file and examples in the configuration documentation.
Note that the configuration kind for images downloaded via https:// and images downloaded via docker:// is different.